Recently, there has been the spotlight on electronic devices (tablet operating systems) which are able to be handled by touching a display surface with a finger or an electronic pen, like a smart phone and a tablet computer.
Further, in tablet operating systems, a predetermined electronic pen sensing region should be set up so as to handle an electronic device by using an electronic pen. A position of the electronic pen which touches the sensing region should be calculated, for example in orthogonal coordinates.
One example of such tablet operating systems is disclosed in Korean patent application publication No. 2008-86829 (hereinafter, referred to as the reference document). In the reference document, loop coils for sensing a position of an electronic pen with respect to any one of axis directions are arranged in an overlapping structure in which at least three loop coils are insulated from each other. Thus, at the time of configuring a position detecting region having a loop coil pattern, a laminate structure of at least six layers is required even when configuring the position detecting area using a transparent conductive material such as ITO, etc., and a transparent insulating sheet. Therefore there is a limitation on transparency. Further, flexibility of the position detecting area itself is reduced with overlapping of a multi-layered sheet.
In addition, in order for the respective loop coils to be insulated from each other and for the ends thereof to be connected together, a vertical structure such as a through hole which passes through insulation layers is required. Therefore it was difficult to form such a vertical structure with transparent insulation sheets so that in the prior art there was no choice but to use opaque, thick and hard sheets. In this way, a tablet in the prior art in which the substrate of an opaque and fixed type is used as an electronic pen sensing region has a limitation on usage methods and applications of the tablet.